In the past, pressure actuated sleeves have been protected from setting pressures with a rupture disc that is set at a higher pressure than the string test pressure, as described in U.S. Pat. No. 8,555,960. US Publication 2014/0102703 uses pressure cycles and an indexing device with Belleville washers to selectively open a sliding sleeve. U.S. application Ser. No. 14/080544 discusses using timers or sensors to operate a ported sleeve without any detailed description as to how this is to be accomplished.
Timers and signal devices add complexity and expense and the present invention accomplishes a time delay economically and reliably. A disintegrating plug is first exposed to well fluids during the pressure test of the string. After a time the plug disintegrates sufficiently to allow tubing pressure access to a second rupture disc mounted in a pressure balanced chamber. Then when it is desired to shift the sleeve the second rupture disc is deliberately broken at a lower pressure level than the test pressure to allow entry of tubing pressure to a piston that is referenced to a low pressure such as atmospheric. The large differential pressure on the piston then shifts the sleeve. The opening of the ports provides formation access for a variety of operations such as fracturing, acidizing, injecting or conditioning. These and other aspects of the present invention will be more readily apparent to those skilled in the arts from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims.